The purpose of this Mentored Patient-Oriented Research Career Development Award (K23) is to enable the candidate, a child psychiatrist, to became an independent research investigating the development pathways and causes of anxiety disorders in preschool children. The research goal is to place preschoolers' anxiety symptoms and disorders within the framework of developmental epidemiology by focusing on two questions: 1. What are the age-specific presentations of anxiety disorders in children ages 2 to 5 years old? (Nosology) 2. What are the relative contributions of genes and environment and their interaction in the early development of anxiety disorders? (etiology). This application details a program of training in infant/young child psychiatry, in behavioral and statistical genetics with an introduction to molecular genetics and genomics, and advanced training in pediatric anxiety disorders. The candidate is based in the Center for Developmental Epidemiology, Duke University Medical Center. Sponsors are child psychiatrists Adrian Angold MRCPsych (developmental psychopathology and measure development), Robert Emde MD, and Charles Zeanah MH (infant/young child psychiatry and assessment of young children), and John March MD (anxiety disorders). Lindon Eaves PhD, a leading behavioral geneticist, will provide mentoring in this area. The research plan includes: 1. A detailed review of current instrumentation for assessing preschool anxiety. 2. A pilot study of 60 children aged 36-72 months, using a multi-informant assessment protocol. DSM-IV and DC:0-3 diagnoses and symptoms will be assessed using the Preschool Age Psychiatric Assessment (PAPA), a structured parent interview developed by the candidate. 3. Analysis of data on 15,500 2-5 year-old twin pairs to examine the contributions of genes and shared and non-shared environmental factors to young children's anxiety symptoms. 4. Submission of an R01 application for a longitudinal, genetically-informed study of the development of anxiety disorders in preschool children. This work will make important contributions to the development of prevention and treatment interventions for young children and will contribute to our understanding of the etiology of childhood psychopathology.